docs: def to_pickle(self, path):
          """Save the current Graph to a pickle.
  
          Parameters
          ----------
          path : str
              File path where the pickled object will be stored.
          """
          if int(sys.version.split(".")[1]) < 7 and isinstance(self, pygsp.graphs.Graph):
              # python 3.5, 3.6
              logger = self.logger
              self.logger = logger.name
          with open(path, 'wb') as f:
              pickle.dump(self, f)
          if int(sys.version.split(".")[1]) < 7 and isinstance(self, pygsp.graphs.Graph):
              self.logger = logger